In so-called integrated analytical elements the aim is that all of the handling of the sample is carried out inside the element. Thus the aim is that the pre-treatment of the sample, its quantitative dosing and the quantitative dosing of reagents can be carried out inside the element and not as separate steps outside the element. When speaking of quantitative analysis, there are certain known devices in which the aim has been an integrated analytical element. Such devices have been disclosed, for example, in GB Pat. No. 1 440 464, U.S. Pat. Nos. 3,992,158, 4,066,403 and 4,363,874, as well as in CA Pat. No. 1,162,075, DE Application No. 31 33 538 and GB Application No. 2,095,404.
All of the above-mentioned publications describe devices in which the zones required for the analysis are placed in layers one above the other. The analyte is dosed into one layer, and in the second layer there occur the suitable reactions on the basis of which the desired response is then determined in one way or another. The publications also describe various improvements in the materials of the zones, the dosing systems, etc.
As mentioned above, hematocrit of whole blood constitutes the biggest hindrance to accuracy. If it is desired to use only plasma or serum of the blood, hematocrit has been eliminated, but the separation requires a separate step and separate apparatus for the separation procedure. In addition to increased work and generally increased difficulty in obtaining the results of the determination, one consequence is that a person trained for the work is required for the work steps.
Another hindrance to accuracy is that the materials used do not necessarily lead to uniform diffusion from one layer to another. Also, the difference in the viscosity of the sample, which is due to, for example, variation of hematocrit, causes problems in reproducibility.